Linear light source device for image reading

ABSTRACT

A linear light source device for image reading is disclosed. The main body of the linear light source device includes at least a light-guided bar and a light source assembly. The light-guided bar is a polygonal column with one of its surface, having stripes thereon, acted as a reflective plane with reflective function. The opposite plane of the reflective plane is a light-exiting plane in convex profile, and all the remaining planes are reflective planes. At least one of the ends of the polygonal column is an incident plane for light beam to enter. Light beam transmits from both of the two ends of the polygonal column (or one end with other end acted as a reflective plane) and uniformly transmits through the convex-shaped light-exiting plane. The light-guided bar of the invention having simple in structure and configuration, compact in volume, high rate of utilization in light energy, and being flexible in changing its length is easy to manufacture with high product yield and low manufacturing cost. In addition, it possesses the merits of having multi-function of generating monochromatic and color lights, high luminance, and low cost.

FIELD OF THE INVENTION

[0001] The invention relates to a linear light source device for image reading, such as scanner, facsimile machine, multi-function office machine, and copy machine.

BACKGROUND OF THE INVENTION

[0002] The image reading device such as scanner, facsimile machine, multifunction office machine, and copy machine etc. needs linear light source to illuminate the targets while the liquid crystal modules needs to illuminate the background. The method utilizes linear light source to combine with the light-guided bar so as to transfer the linear light source into plan light source, in this way, the backlight can provided for liquid crystal panel.

[0003] The current technology of the linear light source device of the image reading aare as follow: (1) utilize cold cathode ray tube (CRT) of the linear light source 110 as shown in FIG. 1; (2) utilize light-emitting diode (LED) array of the linear light source 120 as shown in FIG. 2; (3) utilize LED array plus prismatic lens of the linear light source 130 as shown in FIG. 3; (4) utilize prismatic light-guided bar of the linear light source 140 as shown in FIG. 4; (5) utilize prismatic light-guided bar plus housing of the linear light source 150 as shown in FIG. 5A and FIG. 5B; (6) utilize light-guided bar constituted of the linear light source 160, 170, 180, and 190 by the structure formed by the intersection of prismatic column plane and oblique plane as shown in FIG. 6, FIG. 7, FIG. 8A, FIG. 8B, FIG. 9A, and FIG. 9B.

[0004] The above-mentioned linear light source 110 shown in FIG. 1 is composed of cold CRT 112 and transfer circuit 114. The luminescence of the cold CRT 112 is the same as that of the fluorescent tube (hot CRT) except that it is suitable for small tube diameter since it has the merits of simple in structure and compact in electrode. But this technology needs to have transfer circuit provided, the overall size is relatively large, and as the cold CRT 112 is a cylindrical type of luminaire, the rate of light energy utilization is low and it is unable to generate respectively the light with different wave length. Besides, it is fragile and short in service life.

[0005] As shown in FIG. 2, several LEDs 124, like forty pieces, are mounted on a substrate 122. The rate of light energy utilization is low since the space angle of the radiation can be greater than a half of a space. Moreover, since spaces are existed between the LEDs, and since it is inconsistent in luminous intensity, the light uniformity is poor. Further, since many pieces of LEDs 124 are required to use, the cost is high.

[0006] As shown in FIG. 3, many LEDs 124, like forty pieces, are mounted on a substrate 122. And a prismatic lens 132 is provided. In contrast with FIG. 2, although the addition of this prismatic lens 132 improves the rate-of light energy utilization and light beam uniformity, the rate of light energy utilization is still low. Besides, it has the demerit of being high in cost.

[0007] U.S. Pat. No. 5,400,224 discloses a technology shown in FIG. 4. The light transmits by the use of a prismatic light-guided bar 142 whose cross-section can be a circle, a rectangle, a triangle, an ellipse, or an irregular shape etc. The incident light 200 of the one having incident angle greater than the critical angle transmits into the light-guided bar 142 by total reflection without loss in radiant flux, then goes through the light-guided bar 142 and exits out through the light-exiting plane to become exiting light beam 202. As the light drops on the stripes of the surface, that having incident angle smaller than the critical angle, refract from the stripes 144 of the surface to become out-refracting light 204. In the meantime, in contrast with the surface with stripes, the light also drops on the smooth surface. Those light beams having their incident angle smaller than the critical angle also refract from the smooth surface to become out-refracting light 206. Since the light-guided bar 142 is merely a simple prismatic column and the surface stripes 144 are in simple belt-shape, the light uniformity is poor.

[0008] Japan patent No. 8-163320 discloses a technology shown in FIG. 5A and FIG. 5B. A linear light source 150 is composed of a light-guided bar 152, a light source assembly 300, and a housing 158. The cross-section of a light-guided bar 152 constituted by the prismatic column is a pentagon by cutting a corner of a rectangle or a polygon by cutting two or more corners of a rectangle. The plane formed by cutting an angle is a light-exiting plane 154. The side surfaces other than the two neighboring side surfaces between the light-guided bar 152 and the light-exiting plane 154 are coated with reflective layers 156 (see FIG. 5B). A housing 158 is provided, separating by a thin air layer, between the light-exiting plane 154 and at least a plane other than an end plane of the two end planes provided by a light source assembly 300. This kind of technology increases the size of the device and the cost since the housing 158 is required to provide. The device is apt to generate the light beam having its incident angle smaller than the critical angle. Moreover, the light beam reflected from the plane of the light-guided bar 152 allows only a portion to be reflected from the inner wall surface of the housing 158 and is then refracted back again into the light-guided bar 152, thereby, the rate of light energy utilization is not high. Further, since the device depends merely on the reflective layers 156 to adjust the output radiant flux distribution, hence the uniformity is not good enough.

[0009] Another technology shown in FIG. 6 and FIG. 7 is disclosed by a patent No. 326931 of Taiwan, R.O.C. As shown in FIG. 6, a linear light source 160 is composed of a light-guided bar 162 and a light source assembly 300. The cross-section of the light-guided bar 162, constituted by the intersection of a prismatic column and an oblique plane, is a rectangle. Surface stripe 165 and reflective layers 166 are provided on a oblique surface 164 on the oblique plane, and the light-exiting plane is opposite to the oblique surface 164. The linear light source 170 is composed of a light-guided bar 172 and two-end light source assembly 300. As shown in FIG. 7, the light-guided bar 172 is constituted by the intersection of a prismatic column and an oblique plane. The cross-section of the prismatic column is a rectangle and the oblique plane has two oblique surfaces 174. A light-exiting plane 178 is provided opposite to the oblique surfaces 174. The remaining setups are the same as those in FIG. 6. Since the cross-sections of the light-guided bars 162 and 172 are rectangle, light beam having incident angle smaller than critical angle is easy to generate. As a result, there is a loss of radiant flux, thereby; rate of light energy utilization is poor. Besides, since the device depends merely on the linear variation of oblique planes 164, and 174 as well as the adjustment of the output radiant flux distribution, the light beam uniformity is poor.

[0010] In FIGS. 8A and 8B, a linear light source 180 is composed of a light-guided bar 182 and light source assemblies 300 positioned at both ends. The light-guided bar 182 is constituted by the intersection of a prismatic column and an oblique plane. The cross-section of the prismatic column is an irregular shape (see FIG. 8B). The oblique planes are constituted by two pairs of two oblique surfaces 184, of the light-guided bar 182, inclined in opposite direction. The light-exiting planes 186 are other prismatic column planes of non-cylindrical planes. The surface stripes 188 are on the opposite side of the light-exiting plane 186. Since the cross-sections of the light-guided bars 182 is an irregular shape, light beam having incident angle smaller than critical angle is easy to generate. As a result, there is a loss of radiant flux, thereby; rate of light energy utilization is not high. Further, since the device depends merely on the linear-varied oblique surface 184 to adjust the output radiant flux distribution, hence the uniformity is not good enough.

[0011] In FIGS. 9A and 9B, a linear light source 190 is composed of a light-guided bar 192 and light source assembly 300. The light-guided bar 192 is constituted by the intersection of a prismatic column and an oblique plane. The cross-section of the prismatic column is an irregular shape (see FIG. 9B). The oblique plane is an oblique curved surface, and the light-exiting planes 196 is an irregular prismatic column plane. The surface stripes 198 having surface stripes 198 coated with reflective layer are on the opposite side of the light-exiting plane 196. Besides, a groove 199 formed by two oblique surfaces is provided. Since the cross-sections of the light-guided bars 192 is an irregular shape, light beam having incident angle smaller than critical angle is easy to generate. As a result, there is a loss of radiant flux, thereby; rate of light energy utilization is poor. Further, since the reflective layers is a simple belt-shape and the device depends merely on the oblique curved surface 194 and groove 199 to adjust the output radiant flux distribution, hence the uniformity is not good enough.

[0012] Finally, another technology shown in FIG. 10 is disclosed by a patent No. 420306 of Taiwan, R.O.C. As shown in FIG. 10, the surface stripe of the reflective plane of a light-guided bar is perpendicular to the light axis of the transmitting plane. They are in oblique-tooth shapes with unequal spaces, and the reflective layers appear irregular shapes. The oblique teeth are inclined in a direction away from the light source assembly to facilitate the light transmitting of the reflecting light beam in a direction away from the light source assembly. Although the device has the merits of being compact in size, prominent in light uniformity, high in rate of light energy utilization, and able to change the length of the length of the prismatic column, the manufacturing cost is rather high. The is because that the requirement of precision specification of the mold of the light-guided bar is very rigorous in order to obtain the oblique-tooth shape having unequal spaces. Moreover, the fact that the device needs to be coated with a reflective layer results in high manufacturing cost for providing the mold. Consequently, yield is not easy to raise, thereby, the manufacturing cost remains rather high.

SUMMARY OF THE INVENTION

[0013] The objective of the invention is to provide a linear light source device for image reading. The light-guided bar is simple in structure and configuration, thereby; the requirement for the precision specification is rational and not rigorous. As a result, the manufacturing cost for the mold is low. Moreover, the surface stripes of the reflective layers having surface stripes with reflective function are surface treated for surface roughness only, the reflecting paint does or does not need to be spread or coated. Therefore, the manufacturing yield of an ideal light-guided bar is easy to achieve.

[0014] The another objective of the invention is to provide a linear light source device for image reading wherein the length of the light-guided bar used can be cut to be shorter to become a relatively short light-guided bar.

[0015] Still another objective of the invention is to provide a linear light source device for image reading. The linear light source is illuminated by a point light source, or the point light source obtained through a transfer, which transmits through the light-guided bar to obtain a linear existing light.

[0016] A still further objective of the invention is to provide a linear light source device for image reading. The linear light source can generate respectively the monochromatic light having different wave length, and can be combined into a linear light source with relatively long wave length

[0017] Yet another objective of the invention is to provide a linear light source device for image reading. The linear light source of invention is particularly applicable for the image reading device such as scanner, facsimile machine, multi-function office machine, and copy machine etc. that need linear light source to illuminate the targets, and for the liquid crystal modules that needs to illuminate the background.

[0018] To achieve the above mentioned objectives, the invention provides a linear light source including a light-guided bar and a light source assembly.

[0019] The light-guided bar includes a polygonal main body having at least a tail end plane for light beam to enter; at least two planes in opposite locations of the main body provide a reflective plane with surface stripes and a corresponding light-exiting plane, and the remaining planes constituting reflective layers with reflecting function so that the light beam transmitting into the incident plane and through the transmission of the polygonal main body as well as the multiple reflection of the reflective planes can transmit out of the light-exiting plane

[0020] One of the surfaces of the polygonal main body appearing a convex profile is a light-exiting plane that is not film-coated with white reflective paint while the corresponding reflective plane having surface stripes needs to be film-coated with white reflective paint. The stripes are treated by segmentation such that surface roughness is relatively smooth near the light source while the surface roughness is increased gradually as the stripes are away from the light source according to the increase of the distance from the light source in order to make the light beam uniformly distributed so as to improve the uniformity of the light beam transmitting out of the light-exiting plane. The rest of the surfaces of the polygonal main body being reflective layers having reflective function can be film-coated with white reflective paint. Both the two tail end planes can be incident plane of light beam. If light beam transmits from the light source at both ends through the main body, then the two end planes are not coated with white reflective paint. But if a tail end of the two ends is an incident plane while the other tail end is a reflective plane, then the reflective end plane can reflect the light beam back to the polygonal main body, thereby, the reflective end plane needs to be coated with white reflective paint.

[0021] The light source assembly, which is connected to the incident end of the light-guided bar of the contact-type image sensor (CIS), is employed as the incident light source of the light-guided bar of the contact-type image sensor.

[0022] The light source assembly includes a convex polygonal seat-type positioning plane, a reflective plane, and at least a light-emitting diode (LED) mounting on the mounting plane. The convex polygonal seat-type positioning plane is connected and tightly fitted to the incident tail end of the light-guided bar if CIS where the light-guided bar is perpendicular to the mounting plane of the light source assembly.

[0023] The centerline, which is the light axis of the light source assembly, of the main body of the non-closed polygonal light-guided bar is perpendicular to the mounting plane. A non-closed convex polygonal main body constituting the positioning plane is tightly fitted to the incident end of the convex polygonal light-guided bar of the CIS and the other seat-type plane constituting the positioning plane contacts with the tail end plane of the incident end of the light-guided bar of the CIS.

[0024] Since the positioning plane intersect a non-closed convex type polygonal main body on a plane, and a non-closed convex polygonal main body constituting the positioning plane is tightly fitted to the incident end of the light-guided bar of the CIS, the other plane constituting the positioning plane contacts the end plane of the incident end of the light-guided bar of the CIS. Therefore, the invention possesses the characteristic of high precision on connecting positioning of the incident end of the light-guided bar of the CIS. Consequently, the leaking of the incident light source of the light-guided bar of the CIS is reduced to a minimum. As a result, the invention is superior on the consistency of the distribution of luminous intensity. What is more, at least one of the LED is mounted on the mounting plane by the way that the LED has a distance closest to the light axis and that the LED is uniformly distributed, thereby, the luminous intensity is uniformly distributed and concentrated at the light axis. As a result, the rate of light energy utilization and the light beam uniformity of the connecting to the light-guided bar of the CIS are substantially improved.

[0025] Since all one has to do is to have the incident end of the light-guided bar of the CIS directly plug in that is relying on the tight fitting between a non-closed polygonal main body constituting the positioning plane and the incident end of the light-guided bar of the CIS, the connecting work is accomplished without using the conventional art of molten rivet connection. Therefore, the invention can simplify the art of connecting, and thereby, lower the production cost.

[0026] In order to further understand the objectives, characteristics, and the efficacy of the invention, a detailed illustration with accompanied drawing is performed as follows:

BRIEF DESCRIPTION OF THE DRAWING

[0027]FIG. 1 is a schematic plan view of a cold CRT employed by the linear light source of the prior art.

[0028]FIG. 2 is a schematic plan view of LED array employed by the linear light source of the prior art.

[0029]FIG. 3 is a schematic cross-sectional view of an LED array plus a prismatic column plane employed by the linear light source of the prior art.

[0030]FIG. 4 is a schematic isometric view of a prismatic light-guided bar employed by the linear light source of the prior art.

[0031]FIG. 5A is a schematic isometric view of a prismatic light-guided bar plus a housing employed by the linear light source of the prior art.

[0032]FIG. 5B is a schematic cross-sectional view of FIG. 5A.

[0033]FIG. 6 is a schematic isometric view of a light-guided bar, constituted by the intersection of a prismatic column plane and an oblique plane, employed by the linear light source of the prior art.

[0034]FIG. 7 is a schematic plan view of a light-guided bar, constituted by the intersection of a prismatic column plane and an oblique plane, employed by another linear light source of the prior art.

[0035]FIG. 8A is a schematic plan view of a light-guided bar, constituted by the intersection of a prismatic column plane and an oblique plane, employed by the linear light source of the prior art.

[0036]FIG. 8B is a schematic cross-section view of FIG. 8A.

[0037]FIG. 9A is a schematic plan view of a light-guided bar, constituted by the intersection of a prismatic column plane and an oblique plane, employed by the linear light source of the prior art.

[0038]FIG. 9B is a schematic cross-sectional view of FIG. 9A.

[0039]FIG. 10 is a schematic isometric view of the linear light source of the prior art.

[0040]FIG. 11 is an isometric view of the structure of a light-guided bar of a preferred embodiment of the invention.

[0041]FIG. 12A is a schematic cross-sectional view of the structure of the light-guided bar of the invention.

[0042]FIG. 12B is another schematic cross-sectional view of the structure of the light-guided bar of the invention.

[0043]FIG. 12C is schematic cross-sectional view of the structure of the reflective plane in the light-guided bar of the invention.

[0044]FIG. 13 is the light beam path of the invention.

[0045]FIG. 14 is another light beam path of the invention.

[0046]FIG. 15 is an isometric view of light source assembly of an embodiment of the invention.

[0047]FIG. 16 is an isometric view of light source assembly of an embodiment of the invention.

[0048]FIG. 17A is a schematic mounting diagrams of the light-emitting diodes (LED) of an embodiment of the invention.

[0049]FIG. 17B is a schematic mounting diagrams of the light-emitting diodes (LED) of another embodiment of the invention.

[0050]FIG. 17C is a schematic mounting diagrams of the light-emitting diodes (LED) of another embodiment of the invention.

[0051]FIG. 17D is a schematic mounting diagrams of the light-emitting diodes (LED) of another embodiment of the invention.

[0052]FIG. 18 is a schematic cross-sectional view of the light-guided bar of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053]FIG. 11 is an isometric view of a preferred embodiment of the invention. As shown in FIG. 11, the linear light source 10 of the invention composes of a light-guided bar 20 and light source assembly 30. Essentially, the light-guided bar 20 is an octagonal polygonal main body, and being a symmetrical octagonal column 210, it is selected as a preferred embodiment of the invention. The symmetrical octagonal column 210 includes: an incident plane 220 having at least an end face into which the light beam is allowed to enter while the other end face can be a tail end face 260; a reflective plane 230; a light-exiting plane 240; and a reflective layer 250. A long strip of protuberance 240 is provided on a side surface of the symmetrical octagonal column 210 and is used as the light-exiting plane 240. The reflective plane 230 and the light-exiting plane 240 are provided respectively on the side surfaces of the symmetrical octagonal column 210 and both are opposite to each other. The remaining side surfaces are all for reflective layers 250. The reflective layer 250 is composed of a multiplicity of rectangular planes with their light axes perpendicular to both of the reflective plane 230 and light-exiting plane 240. The reflective layers 250 are connected to the reflective plane 230 and light-exiting plane 240 respectively. Moreover, material used for the symmetrical octagonal column 210 is an optical material with high transmittance and low absorption characteristic such as acrylic-plastic sheets. Preferably, the surface roughness and the refractive index of the light-guided bar 20 is as low as possible as it makes the incident angle of the incident light beam greater than critical angle so that total reflection can be achieved and the loss of the radiant flux is reduced.

[0054] A surface treatment can be performed for the inner surface of the reflective plane 230. FIG. 12A and FIG. 12B are schematic cross-sectional views of the light-guided bar 20 of the invention. As shown in FIG. 12A and FIG. 12B, the types of surface stripe can be classified into two. One of them is that the surface roughness is higher far away from the light source and is lower near the light source. The other one of them is treated by segmentation so that each segment has different surface roughness in order to increase or decrease the coefficients of reflection, refraction, and absorption. A surface having relatively high surface roughness is high in scattering ability and large in reflective angle. Conversely, a surface having relatively low surface roughness is low in scattering ability and small in reflective angle and, in the meantime, can change its radiant flux. Similarly, one can decrease or increase the area of the surface stripe by changing the length of the symmetrical octagonal column 210 in order to adjust the magnitude of the radiant flux to improve the uniformity of the light beam. The light-exiting plane 240 is provided relatively to the reflective plane 230. The reflective layer 250 is composed of a multiplicity of rectangular planes that can connect to both of the reflective plane 230 and light-exiting plane 240. In addition, the light axis, i.e. the X-axis of each of the transmitting plane, is perpendicular to both of the reflective plane 230 and light-exiting plane 240.

[0055]FIG. 13 and FIG. 14 are the light beam paths of the invention. As shown in FIG. 13 and FIG. 14, the light beam entering the incident plane 220 through a multiplicity of reflection of the a plurality of reflective layers 250 so as to improve the light beam uniformity by concentrating the light beam to the reflective plane 230. It then transmits toward the light-exiting plane 240 through the reflection of the reflective plane 230. The light beam uniformity is improved substantially since a surface treatment is performed on the reflective layers 250 of the reflective plane 230. The tail end face 260 at the other end of the symmetrical octagonal column 210 is coated with white or silver color of light-reflective paint by the film-coating method. Thereby, the light can be reflected once more back to the symmetrical octagonal column 210 to further improve the utilization of light energy. Similarly, the incident plane 220, reflective plane 230, and the plurality of light-exiting plane 240 can also be coated with white or silver color of light-reflective paint to facilitate the improvement of utilization of light energy and the index of reflection. It can further reduce the possibility of being absorbed by the material and lower the index of absorption.

[0056] The stripes in inner face of said reflective plane 230 as shown in FIG. 12C can be a groove stripes, wherein the change in width, depth and the method of segmentation of said stripes can cause different roughness, and the roughness of each segment is the same.

[0057]FIG. 15 is an isometric view of light source assembly of an embodiment of the invention. As shown in FIG. 15, the other end of the symmetrical octagonal column 210 can also be an incident plane 280 for the light beam so that both end of the symmetrical octagonal column 210 can allow the entering of the light beam.

[0058]FIG. 16 is an isometric view of light source assembly of another embodiment of the invention. As shown in FIG. 16, the light beam assembly includes a mounting plane 310, a positioning plane 320, and a reflective plane 330 where the mounting plane 310 has the same profile as that of the symmetrical octagonal column 210. Additionally, at least a mounting location is needed for an LCD.

[0059]FIG. 17A through FIG. 17D are schematic mounting diagrams of the light-emitting diodes (LED) of varied embodiments of the invention. As shown in FIG. 17a, an LED 40 is mounted at the center of the circular mounting plane 350. As shown in FIG. 17B, the center lines of two LEDs 40 and the center of the circular mounting plane 350 are in one line, and preferably, the center distance of the two LCDs is as small as possible. As shown in FIG. 17C, the centers of the three LEDs 40 fall within a circle which is preferably as small as possible. The center of the circle coincided with the center of the circular mounting plane 350. Besides, the three lines connecting respectively between the centerlines of the LEDs and the center of the circular mounting plane 350 are formed in 120-degree angles adjacent to one another. As shown in FIG. 17d, the centers of the four LEDs 40 fall within a circle which is preferably as small as possible and the center of the circle coincided with the center of the circular mounting plane 350. In addition, the four adjacent connecting lines connecting successively between the centerlines of the LEDs form a square. As a result, according to the aforementioned illustration, since the LEDs are mounted on the circular mounting plane 350 with their distances that are as close as possible to the light axis and the disposition is uniformly distributed, the luminous intensity of the light beam assembly can concentrate further to the light axis.

[0060] At last, please refer to FIG. 18, the outer part of the octagonal column 210 in light-guided bar 20 can be covered with a polygonal light-reflective sheath 290, wherein the sheath 290 must enclose the reflective plane 230 whose function is for condensing the light that the energy of incident light 200 can be used sufficiently in light.-guided bar 20, and emitted in the other end plane.

[0061] While the invention has been described by way of examples and in terms of a preferred embodiment, it is to be understood that the invention is not limited to the disclose embodiment. On the contrary, it is intended to cover various modifications. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications. 

What is claimed is:
 1. A linear light source device comprising: a light source assembly comprising a non-closed convex positioning plane, at least a reflective plane, at least a mounting plane, and at least a light-emitting diode (LED) mounted on the mounting plane; and a light-guided bar including a convex polygonal column, at least a light-exiting plane, a reflective plane, and a plurality of reflective layers and further including at least a tail end plane of said light-guided bar being an incident plane for light beam to enter, wherein at least two planes in opposite locations of said light-guided bar being a reflective plane with surface stripes and a corresponding light-exiting plane, and the other planes being reflective layers with reflecting function so that the light beam transmitting into the incident plane and through the transmission of the polygonal main body as well as the multiple reflection of the reflective planes can transmit out of the light-exiting plane with relatively uniform light beam.
 2. The linear light source device of claim 1, wherein said convex polygonal column of said light-guide bar is a convex octagonal column.
 3. The linear light source device of claim 1, wherein said centerline of said non-closed convex polygonal positioning plane of said light source assembly is perpendicular to the mounting plane and it is a light axis of the light source assembly.
 4. The linear light source device of claim 1, wherein said convex polygonal positioning plane of said light source assembly intersects the other plane constituting the positioning plane.
 5. The linear light source device of claim 1, wherein a plane of said convex polygonal positioning plane of the light source assembly is parallel to the mounting plane.
 6. The linear light source device of claim 1, wherein said convex polygonal positioning plane of the light source assembly is tightly fit to the incident end of the light-guided bar of the contact-type image sensor.
 7. The linear light source device of claim 1, wherein said centerline of the convex polygonal reflective plane of the light source assembly coincides with the light axis of light beam assembly.
 8. The linear light source device of claim 1, wherein at least a circular and integrated light-exiting outlet of the light source assembly is cut off at the top portion of the reflective plane and the surface of the positioning plane.
 9. The linear light source device of claim 1, wherein a rectangular opening for mounting a light-emitting diode is formed by the intersection of the mounting plane and the constituting bottom portion of the parabolic reflective plane of the light source assembly.
 10. The linear light source device of claim 1, wherein said at least one of the light-emitting diode of the light source assembly is mounted on the mounting plane by the way that it is the closest to the light source and is uniformly distributed.
 11. The linear light source device of claim 1, wherein said light-exiting plane on the light-guided bar structure is appeared to be a convex profile.
 12. The linear light source device of claim 13, wherein said convex light-exiting plane is in a long strip profile whose width can be adjusted in accordance with application so as to achieve an ideal luminous intensity.
 13. The linear light source device of claim 1, wherein said reflective plane has stripes on its surface, and the stripes are treated by segmentation so that each segment has different surface roughness.
 14. The linear light source device of claim 1, wherein said reflective plane of the polygonal column has stripes on its surface, and the stripes are treated by segmentation such that surface roughness is relatively smooth near the light source while the surface roughness increases gradually as the stripes are away from the light source according to the increase of the distance from the light source in order to make the light beam uniformly distributed so as to improve the uniformity of the light beam transmitting out of the light-exiting plane.
 15. The linear light source device of claim 13, wherein said stripes can be groove stripes which are divided at least two segments, the roughness of stripes in every segment is the same but stripes of said segment are different in depth and width.
 16. The linear light source device of claim 1, wherein said surface, having surface stripes, of the reflective plane of the polygonal column is film-coated by silver-white light-reflective paint.
 17. The linear light source device of claim 1, wherein said other end plane of the polygonal column can be a tail end plane for reflecting the light beam that is incident to the plane, back to the main body of the octagonal main body.
 18. The linear light source device of claim 1, wherein said surface of the tail end plane of said light-guided bar is film-coated by silver-white light-reflective paint.
 19. The linear light source device of claim 1, wherein the outer part of said polygonal column can be enclose polygonal light-reflective sheath which must cover the striped of said reflective plane. 